Biodegradable polyester-based polyurethane foams

ABSTRACT

A biodegradable foam which includes a polyester-based polyurethane foam and a mixture comprised of a soil-dwelling carbon-digesting bacteria embedded in a carrier compound. The mixture of the soil-dwelling carbon-digesting bacteria is homogenously dispersed throughout the polyester-based polyurethane foam. This biodegradable foam exhibits biodegradation rates higher than a polyester-based polyurethane foam absent the soil-dwelling carbon-digesting bacteria.

FIELD

The present disclosure relates to biodegradable polyester-basedpolyurethane foams and methods of producing same.

BACKGROUND

Polyurethane (PU) foams are used in many commercial applications such asfootwear, automotive cushioning, mattresses, and many other commercialproducts. PU foams have a very slow rate of biodegradation withpreliminary studies suggesting it would take up to 1000 years to fullydegrade under typical landfill conditions. Improving the biodegradationof the PU foam will reduce the material impact on the environment, asthe material will spend less time in a landfill.

Biodegradation rates of polyurethanes depend on their structure and morespecifically the type of polyol used, with polyester-based PU foamsbiodegrading at a faster rate than polyether-based PU foams, due to thepresence of ester-bonds. However, the presence of ester bonds alone maynot lead to appreciable biodegradation of the PU foam within a desiredtime frame, for example, within 20 years. Additionally, ester bonds playa significant role in the physical and mechanical properties of a foam,where it may not always be desirable or possible to introduce more esterbonds to a PU foam.

Thus, it would be very desirable to provide a method of manufacturing PUfoam that can help control the rate of biodegradation of a PU foam in adesired period of time while simultaneously allowing control of theenvironmental conditions under which the foam is susceptible tobiodegradation, while at the same time not compromising the physical ormechanical properties of the foam during its intended product life.

SUMMARY

The present disclosure provides a method of producing a biodegradablefoam, comprising mixing polyester polyol with i) one or more catalysts,ii) water, and iii) soil-dwelling carbon-digesting bacteria, or asoil-dwelling carbon digesting bacteria embedded in a carrier compoundto produce a mixture. This mixture is mixed with isocyanate to induce achemical reaction between the isocyanate and the water to produce carbondioxide gas, and simultaneously induce a chemical reaction between theisocyanate and the polyester polyol to produce a polyester basedpolyurethane polymer with carbon dioxide bubbles trapped within toproduce said biodegradable polyester-based polyurethane foam, saidbiodegradable polyester-based polyurethane foam. This foam ischaracterized in that it exhibits biodegradation rates which are higherthan the same polyester-based polyurethane foam absent the soil-dwellingcarbon-digesting bacteria.

The carrier compound may be calcium carbonate, zeolite, or sodiumbicarbonate.

The soil-dwelling carbon-digesting bacteria embedded in the carriercompound may be present in said mixture in a range from about 0.001 toabout 10.0 wt. % of the total foam.

The isocyanate may be any one of 4,4′-Methylene diphenyl diisocyanate,2,4-Methylene diphenyl diisocyanate, 2,2′-Methylene diphenyldiisocyanate, 2,4-Toluene diisocyanate, 2,6-Toluene diisocyanate,polymeric methylene diphenyl diisocyanate, or carbodiimide-modifiedmethylene diphenyl diisocyanate.

The method one or more catalysts may be selected to catalyze thereaction between isocyanate and water and simultaneously betweenisocyanate and polyester polyol.

The one or more catalysts may be a tertiary amine catalyst.

The method one or more catalysts are triethylenediamine,N-methylmorpholine, N-methylimidazole, bis(dimethylaminopropyl)amine,dimethylaminoethoxyethanol, Bis-(2-diemthylaminoethyl)-ether,dimethylaminopropylurea,N-dimethylaminopropyl-N-(2-hydroxyethyl)-N-methylamine, orN-dimethylaminoethyl-N-(2-hydroxyethyl)-N-methylamine.

The one or more catalysts may be dibutyltin dilaurate, Tin(II)2-ethylhexanoate bismuth neodecanoate, potassium octoate, potassiumacetate, zinc carboxylates, or nickel carboxylates.

The soil-dwelling carbon-digesting bacteria may comprise at least onestrain of the genus Bacillus.

The soil-dwelling carbon-digesting bacteria may be Bacillus subtilus,Bacillus pumilus, Bacillus licheniformis, Bacillus megaterium, Bacilluscerus, Bacillus alvei, Bacillus coagulans, Bacillus simplex, Bacillusbrevis, or Bacillus amyloliquefaciens.

The method further includes mixing into the mixture surfactants,plasticizers and chain extenders.

The method further includes mixing into the mixture flame retardants,anti-oxidants, cell openers, emulsifiers, hardening agents,non-functional fillers, cross-linking agents, dyes, pigments, or otherhydroxy or amine functionalized materials. The biodegradablepolyurethane foam is characterized by having a modulus in a range fromabout 2 kg/cm2 to about 100 kg/cm2.

The biodegradable polyurethane foam is characterized by having a densityin a range from about 5 kg/m3 to about 1000 kg/m3.

The biodegradable polyurethane foam is characterized by having anelongation at break in a range from about 15 to about 700%.

The biodegradable polyurethane foam is characterized by having a percentmodern carbon in a range from about 0 to about 100%.

The biodegradable polyurethane foam is characterized by having anisocyanate index in a range from about 70 to about 200.

The biodegradable polyurethane foam is characterized by having anaverage isocyanate functionality in a range from about 2.0 to about 6.0.

The biodegradable polyurethane foam is characterized by having apolyester polyol molecular weight in a range from about 500 to about5000 g/mol.

The biodegradable polyurethane foam is characterized by having apolyester polyol average hydroxyl functionality in a range from about1.1 to about 6.0.

The method biodegradable polyurethane foam is characterized by having apolyester polyol hydroxyl number in a range from about 20 to about 300mg KOH/g polyol.

A further understanding of the functional and advantageous aspects ofthe disclosure can be realized by reference to the following detaileddescription and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments disclosed herein will be more fully understood from thefollowing detailed description thereof taken in connection with theaccompanying drawings, which form a part of this application, and inwhich:

FIG. 1 shows a conceptual drawing of a foam block with embedded bacteriahomogenously dispersed throughout the foam; and

FIGS. 2A, 2B, 2C and 2D show photos of foam from disintegration testingbefore (2A) and after an aerobic composting test (ISO 16929) (2B, 2C and2D).

DETAILED DESCRIPTION

Without limitation, the majority of the systems described herein aredirected to biodegradable polyester-based polyurethane foams and methodsof producing same. As required, embodiments of the present disclosureare provided herein. However, the disclosed embodiments are merelyexemplary, and it should be understood that the present disclosure maybe embodied in many various and alternative forms.

The accompanying figures, which are not necessarily drawn to scale, andwhich are incorporated into and form a part of the instantspecification, illustrate several aspects and embodiments of the presentdisclosure and, together with the description therein, serve to explainthe principles of the process of producing biodegradable polyester-basedpolyurethane foams.

The drawings are provided only for the purpose of illustrating selectembodiments of the apparatus and as an aid to understanding and are notto be construed as a definition of the limits of the present disclosure.For purposes of teaching and not limitation, the illustrated embodimentsare directed to biodegradable polyester-based polyurethane foams andmethods of producing same.

Definitions

As used herein, the terms, “comprises” and “comprising” are to beconstrued as being inclusive and open ended, and not exclusive.Specifically, when used in the specification and claims, the terms,“comprises” and “comprising” and variations thereof mean the specifiedfeatures, steps or components are included. These terms are not to beinterpreted to exclude the presence of other features, steps orcomponents.

As used herein, the term “exemplary” means “serving as an example,instance, or illustration,” and should not be construed as preferred oradvantageous over other configurations disclosed herein.

As used herein, the terms “about” and “approximately”, when used inconjunction with ranges of dimensions of particles, compositions ofmixtures or other physical properties or characteristics, are meant tocover slight variations that may exist in the upper and lower limits ofthe ranges of dimensions so as to not exclude embodiments where onaverage most of the dimensions are satisfied but where statisticallydimensions may exist outside this region. It is not the intention toexclude embodiments such as these from the present disclosure.

As used herein, the phrase “polyester-based polyurethane foam” meansthat the foam is produced with at least one polyol component in the foamwhich is a polyester. The advantage of producing a foam with some levelof polyester polyol versus a foam with no polyesters (i.e. polyether,polystyrene, polybutadiene-based foams) is that the ester linkages aremore susceptible to hydrolysis which can lead to a more biodegradablefoam. In addition, polyesters-based foams are known to have improvedmechanical strength properties relative to polyether-based foams.

As used herein, the phrase “soil-dwelling carbon-digesting bacteria”refers to bacteria that can grow under either aerobic and/or anaerobicconditions. When not in a dormant state and under the right conditions,the bacteria break down the polyester-based polyurethane foam by firstexcreting an enzyme that is capable of breaking down the polymers in thefoam into smaller segments at which point the bacteria can digest thesmaller segments and use them as a carbon source for energy and furthergrowth. Examples of soil-dwelling carbon-digesting bacterial include,but are not limited to, Bacillus subtilus, Bacillus pumilus, Bacilluslicheniformis, Bacillus megaterium, Bacillus cerus, Bacillus alvei,Bacillus coagulans, Bacillus simplex, Bacillus brevis, and Bacillusamyloliquefaciens.

The initial breakdown of a polymer, which is the first step of thebiological degradation process, can result from physical and biologicalforces. Physical forces such as heating/cooling, freezing/thawing, orwetting/drying can cause mechanical damage such as cracking of polymericmaterials. The growth of many microorganisms can also cause small-scaleswelling and bursting of polymeric materials. Most polymers are toolarge to pass through cellular membranes, so they must be depolymerizedto smaller monomers before they can be adsorbed and degraded withinmicrobial cells. The monomers, dimers, and oligomers of a polymer'srepeating units are much easily degraded and mineralized because theycan be assimilated through the cellular membrane and then furtherdegraded by cellular enzymes. Two categories of enzymes are involved inthe biological degradation of polymers: extracellular and intracellulardepolymerases. During degradation, exoenzymes from microorganisms breakdown complex polymers, yielding smaller molecules of short chains thatare small enough to pass semi-permeable outer bacterial membranes andthen to be utilized as carbon energy sources. Under oxygen conditions,aerobic microorganisms are mostly responsible for the degradation ofpolymer. Biomass, carbon dioxide, and water are the final products ofdeterioration. As opposite to this, under anoxic conditions, anaerobicmicroorganisms play the main role in polymer destruction. The primaryproducts are methane, water, and biomass. According to the literaturemicroorganisms such as fungi and bacteria are involved in thedegradation process of polyurethanes.

As used herein, the phrase “a carrier compound” refers tonon-interactive or non-functional compound that will not interact ordisrupt the function of the active ingredient with which it is blended.Its function is to act as a transport system for the active ingredientto allow for safer or easier transport and dissolution or dispersioninto another medium. Non-limiting examples of the carrier compound mayinclude Calcium carbonate, Sodium bicarbonate and Zeolite powders.

As used herein, the phrase “polyester polyol” is a polymeric materialthat contains ester functional groups within its backbone structure andcontains 2 or more hydroxyl functionalities. Poly(ethylene adipate),which is a combination of adipic acid (diacid) and ethylene glycol(diol) is an example of a polyester polyol when terminated with ethyleneglycol at both ends. The molecular structure (1) of the poly(ethyleneadipate) polyol is shown below. By using starting materials with morethan 2 functional acid or hydroxyl groups (triols, etc.) it is possibleto produce a branched polyester polyol.

Poly(ethylene adipate)

As used herein, “isocyanate” refers to an organic compound with at leastone isocyanate functional group with the formula R-N═C═O. The molecularstructure (2) of methylene diphenyl diisocyanate containing twoisocyanate functional groups, a common isocyanate used in themanufacturing of polyurethane foams is shown below.

Methylene Diphenyl Diisocyanate

As used herein, the “catalyst” refers to those catalysts that catalyzethe reaction between an isocyanate and water and simultaneously betweenisocyanate and polyester polyol. Non-limiting examples of such catalystsinclude the family of tertiary amine catalysts, such astriethylenediamine, N-methylmorpholine, N-methylimidazole,bis(dimethylaminopropyl)amine, dimethylaminoethoxyethanol,Bis-(2-diemthylaminoethyl)-ether, dimethylaminopropylurea,N-dimethylaminopropyl-N-(2-hydroxyethyl)-N-methylamine, andN-dimethylaminoethyl-N-(2-hydroxyethyl)-N-methylamine. Another exampleis the family of metal-based catalysts, for example, dibutyltindilaurate, Tin(II) 2-ethylhexanoate, bismuth neodecanoate, potassiumoctoate, potassium acetate, zinc carboxylates, nickel carboxylates.

Polyurethane foams are synthetic polymers that exhibit good mechanicalproperties, low material cost, eco-friendliness, and can be used as analternative to solid plastics and other traditional materials. The basicstructure of polyurethanes consists of (1) isocyanate (2) polyol, and(3) chain extender. Generally, a chain extender is a small molecularweight molecule containing 2 or more hydroxy groups that react withisocyanates in the same way as the polyol reacts. An isocyanatefunctional group reacts with hydroxyl functional group to produce aurethane linkage, where this process can be repeated to generate apolymeric chain including a combination of polyol, isocyanate and chainextender molecules. The reaction of isocyanate and polyol to formpolyurethane is shown below.

To produce a PU foam, the presence of a blowing agent is required. Inthis case, water is added where a reaction with an isocyanate functionalgroup will produce a chain reaction that produces carbon dioxide gas, asshown below. An amine is produced from the initial isocyanate group,which will react with another isocyanate group to produce a ureafunctional group, also shown below.

These two reactions described above occur simultaneously to produce a PUfoam consisting of a polymeric network containing urethane, urea, andester functional groups in the backbone of these polymers. Additionaladditives such as catalysts, surfactants, emulsifiers, etc. can be addedto help balance the two reactions described above to produce a stable PUfoam.

To enhance the biodegradability, bacteria such as Bacillus species isadded in powder form using a carrier solid (Zeolite or CalciumCarbonate) that evenly disperses the bacteria throughout the foam.Canadian Patent Application No. 2,828,174 entitled “Impregnated OdourControl Products and Methods of Making the Same” discloses a detailedexplanation on the preparation of a solid powder containing Bacillusspecies. FIG. 1 shows a conceptual drawing of a foam block with embeddedbacteria (dark spots) homogenously dispersed throughout the foam.

Synthesis Flexible Polyester Based Polyurethane Foams

The percentage of constituents for the formulation are commonly providedin a form known as parts per hundred polyol meaning a base polyol has amass of 100 g and all other constituents are based on this base polyol.A good example is WO patent publication:https://patents.google.com/patent/WO2018000095A1/en which isincorporated herein by reference in its entirety. Below is a list ofcommon ingredients and their typical proportion ranges relative to thebase polyol.

Polyester polyol 100 g Chain extender 2-10 g Water 0.5-10 g Catalyst0.1-2.0 g Surfactant 0.5-3.0 g Isocyanate 20-200 g

Optional Constituents

Plasticizer 0-30 g Dye 0-5.0 g Antioxidant 0-1.0 g Flame retardant 0-10g Emulsifier 0-5.0 g

Foam Formulation Specifics

The foam is produced using isocyanate having an index in the range fromabout 70 to about 200, and more preferably in the range from about 90 toabout 115. Isocyanate index refers to the ratio of isocyanate functionalgroups relative to hydroxyl functional groups. An index of 100 means anexact ratio, where lower means less isocyanate relative to hydroxylgroups. The isocyanate has an average functionality in the range from 2to 4, and more preferably 2.1 to 2.5. The polyester polyol molecularweight is in the range from about 200 to about 5000 g/mol, andpreferably in the range from about 2000 to about 3000 g/mol. Thepolyester polyol average hydroxyl functionality is in the range fromabout 1.1 to about 6, and preferably between 2 to 3. The polyesterpolyol hydroxyl number is in the range from about 20 to about 300 mgKOH/g polyol, and preferably in the range from about 30 to about 60 mgKOH/g polyol).

Biodegradable Polyurethane Foam Properties

The resulting biodegradable polyurethane foam as produced herein ischaracterized by a foam density in a range from about 5 kg/m³ to about1000 kg/m³, and more preferably in a range from about 20 kg/m³ to about60 kg/m³. The tensile modulus is in a range from about 2 kg/cm² to about100 kg/cm², and preferably in a range from about 10 kg/cm² to about 50kg/cm², as per ASTM D3574-17 or ASTM D1623.

The resulting biodegradable polyurethane foam also exhibits elongationat break in the range from about 15% to about 700%, and preferably therange from about 200% to about 600% as per ASTM D3574-17 or ASTM D1623.It further exhibits a foam percent modern carbon (pMC) in the range fromabout 10% to about 100% (preferably 50-100%), see the following patentpublication, which is incorporated herein by reference in its entirety.(https://patents.google.com/patent/WO20140275305A1/en)

Table 1 shows the results from an ISO 16929 biodegradation test thatdetermines the degree of disintegration of plastic materials in a pilotscale aerobic compost under defined conditions. Samples were placed in80 Litre polypropylene test chambers with approximately 66 kg ofinoculum. Samples were placed in a polypropylene netting with 5 mm poresmixed with 5 mm sieved compost. 1% bio-waste addition was added. Thetest duration was 90 days, and the temperature profile of the testingchamber over that duration was as follows: T0 (days): 63° C., T7d: 58°C., T14d: 55° C., T21d: 54° C., T28d: 46° C., T35d: 48° C., toapproximately 40° C. for T90 days. FIGS. 2A, 2B, 2C and 2D show photosof foam from disintegration testing before (2A) and after an aerobiccomposting test (ISO 16929) (2B, 2C and 2D).

TABLE 1 Disintegration under aerobic conditions (ISO 16929). Sample %Disintegration Control Foam 11.0 Control + 0.05% bacteria in Zeolite17.9 Control + 0.05% bacteria in Calcium 26.7 carbonate

Table 2 shows the results from another aerobic composting study using amodified version of ASTM D5338 for determining aerobic biodegradation ofpolyurethane foams containing bacteria with and without a carriercompound. Each sample was placed in a separate 1.75 Litre polyethylenetest chamber with 612 g of inoculum which consisted of four layers ofmunicipal compost (400 g in total) and two layers of food scraps (200 gin total) and was topped with a thin layer of coal fly ash (12 g). Thetest duration was 25 days, and the temperature of the testing chamberwas 35° C. for the first two days and 58° C. for the remaining 23 days.

TABLE 2 Disintegration under aerobic conditions when using bacteria andbacteria embedded in a carrier compound. Normalized DisintegrationSample (Sample/Control Foam) Control + 0.025% bacteria in Calcium 1.08carbonate Control + 2.5% bacteria (no carrier) 1.19 Control + 5%bacteria (no carrier) 1.58

Table 3 shows the results from a high-rate dry anaerobic batchfermentation process which was performed according to ASTM D5511. Thisprocess simulates and accelerates biodegradation process which takesplace in a landfill. For each test, 15 g of the sample (milled to <1 mm)and 1 kg of stabilized highly active inoculum were added to a vesselwith volume of 2.5 Litre. The incubation temperature was 52° C.±2° C.and the mixture was left to ferment batch-wise for 16 days.

TABLE 3 Biodegradation under anaerobic conditions (ASTM D5511). Sample %Biodegradation Industry-standard ethylene vinyl acetate (EVA) foam 0.6Industry-standard polyether PU foam −0.1 Biodegradable polyester PUfoam + 0.05% bacteria in 12.6 Calcium carbonate

Thus, to summarize, the present disclosure provides a biodegradablefoam, comprising polyester-based polyurethane foam, and a soil-dwellingcarbon-digesting bacteria or a mixture comprised of a soil-dwellingcarbon-digesting bacteria embedded in a carrier compound, said mixturesubstantially homogenously dispersed throughout said polyester-basedpolyurethane foam, the bacteria-containing polyester polyurethane foamcharacterized in that it exhibits biodegradation rates higher than apolyester-based polyurethane foam absent the soil-dwellingcarbon-digesting bacteria.

In an embodiment, the soil-dwelling carbon-digesting bacteria comprisesat least one strain of the genus Bacillus.

In an embodiment, the soil-dwelling carbon-digesting bacteria isselected from the group consisting of Bacillus subtilus, Bacilluspumilus, Bacillus licheniformis, Bacillus megaterium, Bacillus cerus,Bacillus alvei, Bacillus coagulans, Bacillus simplex, Bacillus brevis,and Bacillus amyloliquefaciens.

In an embodiment, the carrier compound is selected from the groupconsisting of Calcium carbonate, Sodium Bicarbonate and Zeolite.

In an embodiment, the soil-dwelling carbon-digesting bacteria embeddedin a carrier compound is present in said carrier compound, in a rangefrom about 0.001wt % to about 100wt %.

In an embodiment, the soil-dwelling carbon-digesting bacteria embeddedin a carrier compound is present in said polyester-based polyurethanefoam, in a range from about 0.0001 to about 25.0wt % of the total foamand preferably in a range from about .025 to about 10 wt %. It will beunderstood that by varying the amount of bacteria mixed into the PU foamfacilitates fine tuning of the rate of biodegradation, with higheramounts giving faster degradation rates.

A significant advantage to the product and method disclosed herein isthat the rate of biodegradation can be controlled and tuned. The desireddegradation rate of the product will be determined by the use of thefinal foam product. For example, produced products which are highlydisposable (e.g. single use products or products intended to be usedonly a few times-for example single use earplugs) then a higherconcentration of bacteria would be used. On the other hand, productswith longer lifetimes, such as midsoles for footwear would require thatless bacteria would be used as the lifetime of footwear is preferablyyears. The control over the concentration of the bacteria in thepolyurethane foam, and therefore the tunability of the biodegradationrate of the foam, is further enhanced by the feasibility of utilizingpure bacteria as well as bacteria present in a carrier compound, wherepure bacteria yield significantly higher degradation rates.

In an embodiment, the particle size of the bacteria and carriercompounds are equal to or less than about 44 microns. The bacteria andcalcium carbonate particles are both 44 microns where they arephysically blended to obtain the desired concentration of bacteria inthe mixture.

In an embodiment, the soil-dwelling carbon-digesting bacteria embeddedin a carrier compound is present in said polyester-based polyurethanefoam, in a range from about 0.01 to about 0.5 wt % of the total foam.

In an embodiment, the foam is characterized by a tensile modulus in arange from about 5.0 kg/cm² to about 100 kg/cm².

In an embodiment, the foam is characterized by a density in a range fromabout 5 kg/m³ to about 1000 kg/m³.

In an embodiment, the foam is characterized by an elongation at break ina range from about 15 to about 700%.

In an embodiment, the foam has a percent modern carbon in a range fromabout 0 to about 100%.

In an embodiment, the foam is characterized in that it has a modulusequal to or greater than 50 kg/cm².

The present disclosure also provides a method of producing abiodegradable polyurethane foam comprising mixing polyester polyol withcatalysts, water and soil-dwelling carbon-digesting bacteria which areembedded in a carrier compound, to produce a mixture. The methodincludes mixing isocyanate into the mixture to induce a chemicalreaction between the isocyanate and water to produce carbon dioxide gas,and simultaneously induce a chemical reaction between the isocyanate andpolyester polyol to produce a polyester based polyurethane polymer withcarbon dioxide bubbles trapped within to produce said biodegradablepolyurethane foam. The biodegradable polyurethane foam is characterizedin that it exhibits biodegradation rates higher than a polyester-basedpolyurethane foam absent the bacteria.

In an embodiment, the method further comprises adding one or morecatalysts to the mixture, the catalyst being selected to catalyze thereaction between isocyanate and water and simultaneously betweenisocyanate and polyester polyol.

In an embodiment of the method the isocyanate is selected from the groupconsisting of 4,4′-Methylene diphenyl diisocyanate, 2,4-Methylenediphenyl diisocyanate, 2,2′-Methylene diphenyl diisocyanate, 2,4-Toluenediisocyanate, 2,6-Toluene diisocyanate, polymeric methylene diphenyldiisocyanate and carbodiimide-modified methylene diphenyl diisocyanate.

In an embodiment of the method the catalyst is selected from the groupconsisting of triethylenediamine, N-methylmorpholine, N-methylimidazole,bis(dimethylaminopropyl)amine, dimethylaminoethoxyethanol,Bis-(2-diemthylaminoethyl)-ether, dimethylaminopropylurea,N-dimethylaminopropyl-N-(2-hydroxyethyl)-N-methylamine, andN-dimethylaminoethyl-N-(2-hydroxyethyl)-N-methylamine, dibutyltindilaurate, Tin(II) 2-ethylhexanoate bismuth neodecanoate, potassiumoctoate, potassium acetate, zinc carboxylates and nickel carboxylates.

In an embodiment of the method the catalyst is a tertiary aminecatalyst.

In an embodiment of the method the soil-dwelling carbon-digestingbacteria comprises at least one strain of the genus Bacillus.

In an embodiment of the method the soil-dwelling carbon-digestingbacteria is selected from the group consisting of Bacillus subtilus,Bacillus pumilus, Bacillus licheniformis, Bacillus megaterium, Bacilluscerus, Bacillus alvei, Bacillus coagulans, Bacillus simplex, Bacillusbrevis, and Bacillus amyloliquefaciens.

In an embodiment of the method the carrier compound is selected from thegroup consisting of calcium carbonate, zeolite, and sodium bicarbonate.

In an embodiment the method further includes mixing into the mixturesurfactants, plasticizers and chain extenders.

In an embodiment the method further includes mixing into said mixtureflame retardants, anti-oxidants, cell openers, emulsifiers, hardeningagents, non-functional fillers, cross-linking agents, dyes, pigments, orother hydroxy or amine functionalized materials.

In an embodiment the method further includes soil-dwellingcarbon-digesting bacteria embedded in a carrier compound is present inthe mixture in a range from about 0.001 to about 10.0 wt % of the totalfoam.

In an embodiment of the method the produced biodegradable polyurethanefoam is characterized by having a modulus in a range from about 2 kg/cm²to about 100 kg/cm².

In an embodiment of the method the produced biodegradable polyurethanefoam is characterized by having a density in a range from about 5 kg/m³to about 1000 kg/m³.

In an embodiment of the method the produced biodegradable polyurethanefoam is characterized by having an elongation at break in a range fromabout 15 to about 700%.

In an embodiment of the method the produced biodegradable polyurethanefoam is characterized by having a percent modern carbon in a range fromabout 0 to about 100%.

In an embodiment of the method the produced biodegradable polyurethanefoam is characterized by having an isocyanate index in a range fromabout 70 to about 200.

In an embodiment of the method the produced biodegradable polyurethanefoam is characterized by having an average isocyanate functionality in arange from about 2.0 to about 6.0.

In an embodiment of the method the produced biodegradable polyurethanefoam is characterized by having a polyester polyol molecular weight in arange from about 500 to about 5000 g/mol.

In an embodiment of the method the produced biodegradable polyurethanefoam is characterized by having a polyester polyol average hydroxylfunctionality in a range from about 1.1 to about 6.0.

In an embodiment of the method the produced biodegradable polyurethanefoam is characterized by having a polyester polyol hydroxyl number in arange from about 20 to about 300 mg KOH/g polyol.

Therefore what is claimed is:
 1. A method of producing a biodegradablefoam, comprising: a) mixing polyester polyol with i) one or morecatalysts, ii) water, and iii) soil-dwelling carbon-digesting bacteria,or a soil-dwelling carbon digesting bacteria embedded in a carriercompound to produce a mixture, and b) mixing isocyanate into saidmixture to induce a chemical reaction between the isocyanate and thewater to produce carbon dioxide gas, and simultaneously induce achemical reaction between the isocyanate and the polyester polyol toproduce a polyester based polyurethane polymer with carbon dioxidebubbles trapped within to produce said biodegradable polyester-basedpolyurethane foam, said biodegradable polyester-based polyurethane foamcharacterized in that it exhibits biodegradation rates which are higherthan the same polyester-based polyurethane foam absent the soil-dwellingcarbon-digesting bacteria.
 2. The method according to claim 1, whereinsaid carrier compound is calcium carbonate, zeolite, or sodiumbicarbonate.
 3. The method according to claim 1, wherein saidsoil-dwelling carbon-digesting bacteria embedded in the carrier compoundis present in said mixture in a range from about 0.001 to about 10.0 wt% of the total foam.
 4. The method according to claim 1, wherein saidisocyanate is 4,4′-Methylene diphenyl diisocyanate, 2,4-Methylenediphenyl diisocyanate, 2,2′-Methylene diphenyl diisocyanate, 2,4-Toluenediisocyanate, 2,6-Toluene diisocyanate, polymeric methylene diphenyldiisocyanate, or carbodiimide-modified methylene diphenyl diisocyanate.5. The method according to claim 1, wherein the one or more catalystsare selected to catalyze the reaction between isocyanate and water andsimultaneously between isocyanate and polyester polyol.
 6. The methodaccording to claim 1, wherein said one or more catalysts are a tertiaryamine catalyst.
 7. The method according to claim 1, wherein said one ormore catalysts are triethylenediamine, N-methylmorpholine,N-methylimidazole, bis(dimethylaminopropyl)amine,dimethylaminoethoxyethanol, Bis-(2-diemthylaminoethyl)-ether,dimethylaminopropylurea,N-dimethylaminopropyl-N-(2-hydroxyethyl)-N-methylamine, orN-dimethylaminoethyl-N-(2-hydroxyethyl)-N-methylamine.
 8. The methodaccording to claim 1, wherein said one or more catalysts are dibutyltindilaurate, Tin(II) 2-ethylhexanoate bismuth neodecanoate, potassiumoctoate, potassium acetate, zinc carboxylates, or nickel carboxylates.9. The method according to claim 1, wherein said soil-dwellingcarbon-digesting bacteria comprises at least one strain of the genusBacillus.
 10. The method according to claim 1, wherein saidsoil-dwelling carbon-digesting bacteria is Bacillus subtilus, Bacilluspumilus, Bacillus licheniformis, Bacillus megaterium, Bacillus cerus,Bacillus alvei, Bacillus coagulans, Bacillus simplex, Bacillus brevis,or Bacillus amyloliquefaciens.
 11. The method according to claim 1,further including mixing into said mixture surfactants, plasticizers andchain extenders.
 12. The method according to claim 1, further includingmixing into said mixture flame retardants, anti-oxidants, cell openers,emulsifiers, hardening agents, non-functional fillers, cross-linkingagents, dyes, pigments, or other hydroxy or amine functionalizedmaterials.
 13. The method according to claim 1, wherein saidbiodegradable polyurethane foam is characterized by having a modulus ina range from about 2 kg/cm² to about 100 kg/cm².
 14. The methodaccording to claim 1, wherein said biodegradable polyurethane foam ischaracterized by having a density in a range from about 5 kg/m³ to about1000 kg/m³.
 15. The method according to claim 1, wherein saidbiodegradable polyurethane foam is characterized by having an elongationat break in a range from about 15 to about 700%.
 16. The methodaccording to claim 1, wherein said biodegradable polyurethane foam ischaracterized by having a percent modern carbon in a range from about 0to about 100%.
 17. The method according to claim 1, wherein saidbiodegradable polyurethane foam is characterized by having an isocyanateindex in a range from about 70 to about
 200. 18. The method according toclaim 1, wherein said biodegradable polyurethane foam is characterizedby having an average isocyanate functionality in a range from about 2.0to about 6.0.
 19. The method according to claim 1, wherein saidbiodegradable polyurethane foam is characterized by having a polyesterpolyol molecular weight in a range from about 500 to about 5000 g/mol.20. The method according to claim 1, wherein said biodegradablepolyurethane foam is characterized by having a polyester polyol averagehydroxyl functionality in a range from about 1.1 to about 6.0.
 21. Themethod according to claim 1, wherein said biodegradable polyurethanefoam is characterized by having a polyester polyol hydroxyl number in arange from about 20 to about 300 mg KOH/g polyol.